Front impact damper

ABSTRACT

A front impact damper having a vertical supporting member secured firmly to the ground, and a number of deformable tubular members fitted vertically inside one another and fixed to the vertical supporting member at a given height off the ground; the deformable tubular members each being defined by a portion of W- or triple-groove-section corrugated sheet metal bent appropriately to form a cylindrical tubular body with a corrugated lateral wall.

[0001] The present invention relates to a front impact damper.

BACKGROUND OF THE INVENTION

[0002] As is known, front impact dampers are deformable metal structureserected along the outer edge of a highway, at forks, median strips, gapsin guardrails, or to shield trees, reinforced concrete pillars andsimilar obstacles along the edge of a highway, to stop vehicles headedtowards the obstacle, to gradually absorb all the kinetic energy of thevehicle, and so ensure deceleration below current regulation thresholds.

[0003] At present, the most commonly used front impact dampers comprisea prismatic, triangular- or trapezoidal-base tank made of plasticmaterial, secured to the ground immediately upstream from the obstacle,and filled with water to absorb vehicle impact.

[0004] Another widely used front impact damper comprises a supportingpost fixed vertically into the ground immediately upstream from theobstacle; and a deformable tubular metal member fixed vertically to thetop end of the supporting post and projecting on the opposite side tothe obstacle.

[0005] Front impact dampers of the above type have the major drawback offailing to provide for effectively absorbing the kinetic energy of thevehicle, and can therefore only be erected along relatively slow roads.

SUMMARY OF THE INVENTION

[0006] It is an object of the present invention to provide a frontimpact damper with a much greater capacity to absorb the kinetic energyof the vehicle as compared with currently used dampers.

[0007] According to the present invention, there is provided a frontimpact damper, characterized by comprising a vertical supporting membersecured firmly to the ground; and a number of deformable tubular membersfitted inside one another and fixed to said vertical supporting memberat a given height off the ground.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] A non-limiting embodiment of the present invention will bedescribed by way of example with reference to the accompanying drawings,in which:

[0009]FIG. 1 shows a side view of a front impact damper in accordancewith the teachings of the present invention;

[0010]FIG. 2 shows a plan view of the FIG. 1 front impact damper;

[0011]FIGS. 3 and 4 show a side view and plan view respectively of avariation of the front impact damper in FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE INVENTION

[0012] Number 1 in FIGS. 1 and 2 indicates as a whole a front impactdamper specially designed for location upstream from a small-sizeobstacle along the edge of a highway—e.g. the end of a median strip ofsimilar— to stop vehicles headed towards the obstacle, gradually absorball the kinetic energy of the vehicle, and so ensure deceleration belowestablished thresholds.

[0013] Two or more front impact dampers 1 may obviously be located sideby side along a stretch of the edge of a highway to form a short roadbarrier particularly suitable for shielding medium-size obstacles, suchas large trees, boundary walls or reinforced concrete pillars.

[0014] Front impact damper 1 substantially comprises a verticalsupporting member 2 secured firmly to the ground; and a number ofdeformable tubular members 3 fitted inside one another and fixedpreferably, though not necessarily, vertically to vertical supportingmember 2 at a given height off the ground.

[0015] More specifically, in the example shown front impact damper 1comprises three deformable tubular members 3 fitted inside one another,and each defined by a single portion of W- or triple-groove-sectioncorrugated sheet metal 4 bent into a loop to overlap the two ends and soform a cylindrical tubular body with a corrugated lateral wall and aconstant radius of curvature.

[0016] The three deformable tubular members 3 must obviously decreasegradually in outside diameter to fit easily inside one another and allowa certain amount of mechanical clearance between them.

[0017] Deformable tubular members 3 may obviously be other thancylindrical, e.g. as opposed to a circular section, may have a square,rectangular, octagonal, or at any rate closed-polygonal section,preferably, though not necessarily, with rounded corners.

[0018] In this case too, deformable tubular members 3 may be formed froma single portion of corrugated sheet metal bent, if necessary, with avariable or constant radius of curvature.

[0019] With reference to FIG. 2, in the example shown, thelargest-diameter, i.e. outer, deformable tubular member 3 is positionedvertically with its outer lateral surface resting on the top end ofvertical supporting member 2; and the other two deformable tubularmembers 3 are positioned vertically one inside the other and both insidethe outer deformable tubular member 3, so as to rest one on the other atthe point at which outer deformable tubular member 3 is secured tovertical supporting member 2, thus enabling all three deformable tubularmembers 3 to be secured simultaneously to vertical supporting member 2.

[0020] In other words, the three deformable tubular members 3 aretangent to one another at the fastening point to vertical supportingmember 2, so that one set of through bolts can be used to secure allthree deformable tubular members 3 to vertical supporting member 2.

[0021] With reference to FIGS. 1 and 2, in the example shown, verticalsupporting member 2 is defined by an H- or U-section metal bar 5 drivenvertically straight into the ground, and by two collapsible spacermembers 6 interposed between the top end of metal bar 5 and the body ofouter deformable tubular member 3.

[0022] In the example shown, each collapsible spacer member 6 is fixedto the top end of metal bar 5 by a number of through bolts insertedinside slots formed in the two wings of bar 5.

[0023] Operation of front impact damper 1 is easily deducible from theforegoing description with no further explanation required.

[0024] The advantages of front impact damper 1 as described andillustrated herein are obvious: providing two or more deformable tubularmembers 3 fitted inside one another greatly increases the amount ofkinetic energy that can be absorbed in the event of impact by a vehicletravelling in direction d, while the mechanical clearances betweendeformable tubular members 3 enable them to deform sequentially toabsorb the kinetic energy of the vehicle more gradually and so reducemaximum deceleration of the vehicle.

[0025] Clearly, changes may be made to front impact damper 1 asdescribed and illustrated herein without, however, departing from thescope of the present invention.

[0026] More specifically, in the FIGS. 3 and 4 variation, eachdeformable tubular member 3 may be defined by a single portion of W- ortriple-groove-section corrugated sheet metal 7 bent substantially into aC, i.e. without overlapping the two ends, so as to form a cylindricaltubular body with a corrugated lateral wall, a constant radius ofcurvature, and a through longitudinal slit extending the full height ofthe cylindrical tubular body.

[0027] In this case, as opposed to being tangent to one another at thesame point, the three deformable tubular members 3 are tangent at thelongitudinal slit, so that the two end portions 7 a of the portion ofcorrugated sheet metal 7 of each are superimposed on the correspondingend portions 7 a of the other two portions of corrugated sheet metal 7defining the other two deformable tubular members 3.

[0028] In the FIG. 4 variation, vertical supporting member 2 is definedby two U-section metal bars 8, each fixed vertically directly on theground so as to face a respective end portion 7 a of the portion ofcorrugated sheet metal 7 defining each deformable tubular member 3; andby two pairs of collapsible spacer members 9, each pair of which isinterposed between one of the two end portions 7 a of the three portionsof corrugated sheet metal 7 and the corresponding metal bar 8.

[0029] It should be pointed out that, in the example shown, eachcollapsible spacer member 9 is fixed stably to end portions 7 a of thethree portions of corrugated sheet metal defining the three deformabletubular members 3 by means of through bolts, rivets, or similarfastening systems, but is fixed to the top end of metal bar 8 by one ormore through bolts inserted inside slots formed atprogrammed-deformation portions of collapsible spacer member 9.

1) a front impact damper (1), characterized by comprising a verticalsupporting member (2) secured firmly to the ground; and a number ofdeformable tubular members (3) fitted inside one another and fixed tosaid vertical supporting member (2) at a given height off the ground. 2)A front impact damper as claimed in claim 1, characterized in that saiddeformable tubular members (3) are fixed substantially vertically tosaid vertical supporting member (2). 3) A front impact damper as claimedin claim 1, characterized in that said deformable tubular members (3)are fitted inside one another with mechanical clearance. 4) A frontimpact damper as claimed in claim 3, characterized in that saiddeformable tubular members (3) are fitted inside one another so as to betangent to one another at the same point. 5) A front impact damper asclaimed in claim 1, characterized in that at least one said deformabletubular member (3) comprises a portion of corrugated sheet metal (4, 7)having a W- or triple-groove-shaped section, and bent appropriately toform a cylindrical tubular body with a corrugated lateral wall. 6) Afront impact damper as claimed in claim 5, characterized in that saidportion of corrugated sheet metal (4) with a W- or triple-groove-shapedsection is bent into a loop. 7) A front impact damper as claimed inclaim 5, characterized in that said portion of corrugated sheet metal(7) with a W- or triple-groove-shaped section is bent into a C. 8) Afront impact damper as claimed in claim 1, characterized in that saidvertical supporting member (2) comprises at least one metal bar (5, 8)fixed substantially vertically to the ground; said deformable tubularmembers (3) being fixed to the top end of said at least one metal bar(5, 8). 9) A front impact damper as claimed in claim 8, characterized inthat said vertical supporting member (2) comprises at least onecollapsible spacer member (6, 9) interposed between the top end of saidmetal bar (5, 8) and the body of at least one said deformable tubularmember (3). 10) A front impact damper as claimed in claim 1,characterized in that said deformable tubular members (3) are three innumber. 11) A road barrier, characterized by comprising a number offront impact dampers (1) as claimed in claim 1.